v4.0

What's Changed

• Improve error handling of invalid workflow_engine_parameters by @tetron in #71
• Update connexion & toil version. by @DailyDreaming in #72
• 2020 refresh by @mr-c in #89
• drop unneeded subprocess32 by @mr-c in #90
• Update ruamel-yaml requirement from < 0.16 to <= 0.16.5 by @dependabot-preview in #81
• [Snyk] Security upgrade debian from 9 to buster by @snyk-bot in #109
• Upgrade to GitHub-native Dependabot by @dependabot-preview in #102
• Fix tests by @mr-c in #110
• Formal py3.6 support by @mr-c in #113
• Update ruamel-yaml requirement from <=0.16.5,>=0.15.78 to >=0.15.78,<0.17.11 by @dependabot in #111
• Toil 5.6.0 by @mr-c in #128

Full Changelog: v3.3...v4.0